Known in the past has been a device using an image capturing means provided in a vehicle for detecting a condition of a driver of the vehicle. For example, Japanese Patent Publication No. 2016-057839A describes that a facial direction of the driver and an angular velocity of the facial direction is calculated from an image of the driver captured by the image capturing means and, if the facial direction of the driver is outside an image capturing range of the image capturing means, the facial direction is estimated based on the angular velocity of the facial direction.